Broken exhaust manifold studs

[mole42]

Has anyone tackled broken exhaust manifold studs? One of mine has one broken off flush with the flange and another one is a non-original part I obtained from Rimmers before I learned not to. I'd like to change all three but they resist attempts to move them. So far I've used a lot of torque while applying a mapp gas/oxygen flame which gets the cast iron reddish but the studs still won't move. I'm probably going to have to set the manifold up in my drill press and drill them out.

[Phil S]

You can try putting a nut over the broken off stud and welding the nut to the stud. Fill the nut with weld in 2 goes. This can shock the stud and loosen it once its cooled a bit try rocking it back and forth with a spanner.
if not its a case of drilling it out and either helicoils or stepped studs

[Tonywhite]

If you end up needing another manifold with three studs I have some which can be purchased very cheaply

[Goldstar]

Has anyone tackled broken exhaust manifold studs? One of mine has one broken off flush with the flange and another one is a non-original part I obtained from Rimmers before I learned not to. I'd like to change all three but they resist attempts to move them. So far I've used a lot of torque while applying a mapp gas/oxygen flame which gets the cast iron reddish but the studs still won't move. I'm probably going to have to set the manifold up in my drill press and drill them out.

I ended up drilling 3/6 out but it was a pain. Decent drills, slow speed and lube. You also have to get the holes straight or the fitting of the exhaust flange is a nightmare.